This invention relates to optical waveguides and more particularly to a switch arrangement for switching radiation from one waveguide to another and for modulating optical signals.
Optical radiation has been switched in and out of optical waveguides by use of gratings, prisms, and acousto-optic devices. Optical radiation has been switched from one waveguide to another by use of parallel waveguides in which one or both waveguides included a section of electro-optical material whose index of refraction is changed by an electrical voltage. Electrodes placed parallel with spaced waveguides have also been used, as shown in U.S. Pat. Nos. 3,909,108 and 3,964,819. The device of U.S. Pat. No. 3,909,108 requires that electro-optic interaction occurs over a critical length which is voltage-independent but depends upon the coupling constant between the two waveguides. U.S. Pat. No. 3,964,819 requires a 3dB coupler at each end of each waveguide which adds to the length of the device. In prior art devices, the lengths of the waveguides in which radiation is transfered are critical in order to present the proper coupling length.